Issue 2 The Eventider's News Spring/Summer 2004
Back issues - 1
SOME THOUGHTS ON ENGINES
'FIDDLERS GREEN', our Eventide 26, (actually 27'3" if we are forced to admit it!), in 1993 was fitted with a new 17 bhp 'Beta Marine diesel. This has raised a few eyebrows and queries about the extra weight; size etc. Before I quash those queries, maybe I best give some of the background to my decision.
Those of you with long memories may remember back over 20 years to when I was sailing an Eventide 24, 'BLUENOSE'. I replaced her ancient inboard with a lovingly rebuilt Stuart Turner, that was older than me!! At 8 bhp. it was a perfect job. Others with the same engine could not touch us for speed. Why? Propeller sizing.... Using a much thumbed set of computer tables, I ordered a prop, slightly less in pitch than the manufacturers recommended. Result, engine revs spot on.. Speed 5knots (just over), which is what I'd expect from a 24. Lesser horse powers may also give similar results in calm conditions, if the prop sizing is correct.
In theory bhp. needed can equal the length of the water-line in metres and give the same numerical speed in knots. i.e. 5 bhp. in a boat with 5 metres water-line will give a speed of 5 knots. Which as a rule of thumb for our size of boat is not far out. However; as soon as a breeze on the nose is encountered you may have to double than power to get any where. This is because of the wind resistance, [Over about 40 m.p.h. vehicles use more power overcoming wind or air resistance, than anything else.)
If you want to work out the maximum speed of your boat there is a way. . . . The Square Root of the Water-line length, in feet multiplied by 1.3, gives the Speed, in Knots. It works. Any more on your log than that and it's time to check the log, or you are surfing down big ones and a reef may be prudent!!
Back to 'Fiddlers', when launched, she was fitted with a new and unused Stuart Turner 10 bhp. ( it had been in store for years) . With a suitably matched propeller speed was logged at 5.8 knots, in still water. Not bad.
However whilst in the Netherlands in 1992 we had to motor against a head wind on one of the tide less inland seas. Our speed was dropped to just 2 Knots. That was just wind, not sea. It was obvious that more horse power was needed. Over lunch with Maurice, on several occasions recently, the subject of engine power has come up. Maurice commended the new lightweight Japanese diesels, indeed we were both driving excellent Japanese cars. Maurice is inclined to say that, if he were sailing today he would fit a powerful modern lightweight diesel, and for the Eventide 26, 15 to 18 bhp. would not be out of place. With today’s crowded moorings it may well be difficult, if not foolhardy, to sail back in the old style, also with the pressures on us now, to be there yesterday, we do need that extra speed sometimes. So the 17 bhp. engine for 'Fiddlers is not so far out. But what of the weight and size???? Well at 98 kilos, it is 15 kilos LIGHTER than the old Stuart. It is also smaller, considerably so, 4" in length and 2" in width. Height about the same. In January 94, I had only run the engine ashore for about half an hour, running from a bucket of water, fed by hose. This has enabled all joints and seals to be checked and the powerful purr to be appreciated! Three tiny pistons gives a smooth sounding exhaust. Since then I have clocked many happy and economic hours motoring time!
I was also able to check out the ADVERC battery management system, it really does produce 55 amps, for at least 20 minutes. (I had not charged the Ni-Cad batteries since the previous May). During this time however I could not throttle back fully or the engine would have stalled, so great was the power demand of the alternator. As the demand slackened however I was able to get the, now nicely warmed up, engine to tick over beautifully. I was amazed at the quantity of water passing out of the exhaust, I can now see why I was assured that any mud from my creek would be fast ejected by the water pump. All the careful work seems to have paid off No leaks or loose bits, I looked forward to launch day, and about 6.5 to 6.75 knots, which is the top speed I have achieved under sail! In practice top speed under motor is 6 knots, but only for a short burst. Cruising 5 knots quiet cruising 4.5 or so. Those who have sailed in company with us will vouch that she is no sluggard!! Because of the drag factor of the bilge keels, speed under power is normally slightly less than under sail, also if you reach that, so called, 'hull speed' and continue to pour on the power, the stern will squat, causing more drag, and wash!! but little extra speed.
As a result of all my delving into powers, may I recommend the following:- E.24, between 6 and 12 bhp. E.26 needs between 8 and 18 bhp. Don't forget to allow for the manufacturers power losses in pumps, gearboxes and alternators. Our 17 bhp reduces to approx 14 at the prop. That is the starting point for our computer tables, we shall see if it works out later. (Incidentally the engine manufacturer must use the same program, as independently, we have arrived at the same prop!) I’d encourage builders to think seriously and put an appropriately sized engine in, in the first instance, rather than year or two later. . . . . .
John Williams 1387E 'Fiddlers Green'
As a post script to this article we have now had many seasons with the engine, we are overjoyed. Top speed is about 6knots, as expected, but we can still keep up speed when motoring against stiff head winds. Fuel economy is a litre an hour, not a gallon, as with the Stuart. People who watch us motor in and out of our marina ask if we are solar powered, so quiet is the engine. A few years back we re-pitched the prop, adding an inch, this over props the motor slightly so top revs are limited to 3000, not 3500. It means the top speed is not altered but the engine revs less and is even quieter!! We have also updated the fan belt to ‘A’ section. That cured an annoying tendency for them to fray.
Looking down into 'Fiddler's Greens' Engine box. 17 hp Beta nestles nicely in there!
When I launched 'FIDDLERS GREEN', I equipped her with two banks of Ni-cad Batteries. 120 amp hours for services and 60 amp hours for engine start. Up till then I had used an ex-vehicle Lucas 17 ACR alternator, with a hand regulated current control, with success. However when I bought the new 17 bhp. BETA MARINE engine the alternator option I chose was a new Lucas 55 amp marine unit. It did not lend itself to the hand regulation, nor would it have been guaranteed! Add to that the worry that other skippers/friends using 'Fiddlers' had to be 'aufait' with the slight vagaries of the system, i.e. not allowing too much charge for too long and boiling the cells...... To avoid problems I was persuaded to go down a slightly different route.
At this point let me give you a little background. At work I trained the officers of Thames Division, Metropolitan Police. We had a problem with the batteries on our main training boat, a twin screw, 500plus bhp., 34 footer. I suggested that a 'TWC' battery controller may help, and to my surprise, the powers that be agreed. Swale Marine of Queenborough were contracted to fit the devices, now called 'ADVERC' systems.
So successful was the experiment that all the rest of the fleet, some twenty vessels, six of them twin engined, were fitted and no further battery problems occurred......... The system works by over-riding the normal regulator, instead a small computer constantly checks the state of the batteries and can charge them almost back to 100% This happy state does not exist in a conventional, car type, set up. 75% may be possible, over that normal systems just cause the electrolyte to boil off and this has to be replaced, by frequent topping up. This also means that your 100amp hour battery now, at best, can only give you 75 amp hours. The rest, that you paid for, you will never see......
None of those snags apply to the 'ADVERC' system, in addition there is a sensor to detect temperature in the battery box too. If the batteries are warm, the charge rate is decreased. 'FIDDLERS GREEN' now has an 'ADVERC' controller, with it's extra warning light, plus two 30 amp ammeters, on her main switch board, to monitor the charge. The charge is split automatically, by a diode splitter, which the 'ADVERC' allows for and ensures full batteries. Look out for us afloat, we are the ones that have nav lights like the Q.E.2!!!!!!!!
Post Script.The sting in the Tale!!!!
6 Years later the ‘Adverc’ was found to have been supplied with a defective wiring harness and was only in intermittent contact because a vital component had not been soldered in. This was never found before as we rarely used the motor for long enough to overcharge the cells. It was the heat sensor in the battery compartment. Strangely the Adverc ‘failed dangerous’. When the wire was detached, the alternator was pushed into full output, in our case 55 amps. On our trip to the West Country in 2000, the batteries were boiled and very nearly caught fire. Had they been lead acid they may well have exploded. It cost me the replacement of ¾ of the cells on board! The firm replaced the wiring harness but falsely accused me of tampering with it! Needless to say with any company as slippery as this one, I got no further with them. Since I have learnt of others who have had the same problem and I am changing the system to a ‘Sterling’ charger, as soon as I raise the money! In the meantime I bought a voltmeter to monitor the device, like a hawk! Be Warned.
I was fortunate to be able to replace the NiCad Cells for less than the cost of a car battery, but sadly the supply has now ceased, so in 10 years or so, when they pack up, I will have to buy some thing different. By then who knows what sort of battery we might be using.
Speedseal Pump Cover
During the first couple of seasons with our Beta engine ‘Fiddler’s Green’ has been plagued with Jabsco pump impeller problems. I was getting through them at the rate of three a season. I had become a dab hand at removing the pump cover in a jiffy, but I lost a couple of those annoyingly small screws in the bilge in the process. OK you can get away with one missing, but it meant a special trip to buy a stock of replacements. Imagine my surprise to be offered a ‘Speedseal’ cover to test!! I was about to buy one...
Having discarded (as far as the spares box), the original cover and screws, with paper gasket. I carefully unpacked the ‘Speedseal’. I was a little uneasy about the tiny ‘O’ ring seal that had to be fitted, and was not convinced that it would stay in place until I had fitted and removed the cover several times!! Needless to say it stayed put and the cover didn’t leak, even though there are now only 4 not 6 fasteners, and they are hand tightened with large knurled knobs. Only two of the four have to be removed, the remaining pair, that have marks you can feel on the heads, just slackened, clever. They claim you can undo and replace the cover blindfold, not something I’ve tried, but I can tell you it now takes seconds to remove it and replace the impeller, and no tools needed!! I can recommend the ‘Speedseal’, though just to be on the ‘safe’ side I asked for a spare knurled screw and ’O’ Ring. (Ever the pessimist).
Since the initial tests I have not had to replace the impeller again, the cure for that? Fit the manufacturers replacement, not one from a chandler, that was old, probably stiffened with age and I later learnt, with the wrong number of vanes, instead of 6 the correct one has 10!! Live and learn.
As a postscript to this, in 2004 I replaced the 'O' ring seal, for the first time! It had stretched everso slightly and was difficult to refit, so I put on the spare I carry. I called Speed seal to buy replacements, they sent 2 free of charge! How's that for service!
‘Speedseal’ Safety Covers,
30A Merrylands Road,
Surrey. KT23 3HW
Tele. 01372 451992
This evil looking bit of kit has been on my prop shaft for 3 years now. It really deters you from touching the propeller! The serrated teeth are strong enough to chop through the toughest rope without a moments hesitation! I fitted it in early 2000 before we sailed off to Cornwall, just in case! I had only ever once caught anything around my prop, yes it was the dinghy painter! So as not to have the same problems with all those lobsterpots we had heard about, we bought this. It did slow the top speed under power by a fag paper, possibly 0.2 of a knot... But the peace of mind....
The Stripper is available from Ambassador Marine, 252 Hursley, winchester SO21 2JJ. Tele 01962 775405.